Effects of arsenic on seed germination and physiological activities of wheat seedlings

The effects of arsenic(As)were investigated on seed germination,root and shoot length and their biomass and some other factorsto elucidate the toxicity of As.The results showed low concentrations of As(0-1 mg/kg)stimulated seed germination and thegrowth of root and shoot,however,these factors all decreased gradually at high concentrations of As(5-20 mg/kg).The contentsof O2.-,MDA,soluble protein and peroxidase(POD)activity all increased with increasing As concentrations.Soluble sugar content,ascorbate peroxidase(APX),and superoxide dismutase(SOD)activities decreased at low concentrations of As,and increased at highconcentrations of As.While acetylsalicylic acid(ASA)and chlorophyll contents,catalase(CAT)activity displayed increasing trendwhen the concentrations of As was lower than 1 mg/kg,and then decreasing trend.By polyacrylamide gel electrophoresis(PAGE),Asinduced the expression of POD isozymes of wheat seedlings.As induced the expression of CAT isozymes but inhibited the expressionof SOD isozymes of wheat seedlings at concentrations lower than 1 mg/kg.However,As inhibited the expression of CAT isozymes butinduced the expression of SOD isozymes at concentrations higher than 5 mg/kg.The results indicated As could exert harmfulness inthe early development stage of wheat at inappropriate concentrations.